No idea what the push button is for- someone added that. You’ll want to trace the wiring on that button to see what its all about.

The signal wires go up under the seat, in the back. Two bullet connectors. I’d disconnect those and put a volt meter/test light in them, see what you get when you hit the signal. If you’re getting power there, then something’s likely wrong with the signal itself, if not, something else is going on.

In addition to what Jimbob said, I don't know if they'll reach, but you might be able to swap the wires for the left and right and see it works on the other side and vice versa. Also, does it flash with the 4-ways on?

The rear left side turn signal is notorious for having corrosion issues. As the bike sits on the sidestand, any moisture the bike went thorug on a ride migrates down the turn stalk and sits. Many have taken to siliconing the end of the turn stalk, on the inside of the fender, to seal it off. Yours looks pretty clean though on the outside, could be corroded in the socket underneath the pad with the bulb connections.That button underneath the seat, thats an interesting one, no idea what purpose that would serve. I'd trace that back make sure it's not a factor somehow. weird.

as Vic noted, it's common, and usually traced back to a corroded connection inside the base of the socket, where the wire is soldered to that "base contact", on the backside of the insulator. Or the actual Solder Blob on the front, either one...Clean that contact with sandpaper, and also the inside of the socket walls, and spray some contact cleaner in and blow it all out with compressed air.Actuate the 4 way flashers, and check for volts at the contacts using a VOM.

if no juice present, the wire is compromised behind the inner base of the socket, pick up a used one for a couple bucks on e-bay., or install some aftermarket ones...

oh, I forgot to mention, make sure the bulb you use is good, and the correct one... and scrub those connections on the bulb with sandpaper also..

I have to laugh a bit, one of the worst injuries I ever had working on these bikes, was from trying to replace a corroded in left rear turn signal bulb... the biotch "exploded" and shattered between my thumb and fingers when I was trying to get it removed...cut 2 fingers and my thumb. and bled like a stuck pig....and I had to pluck shards of glass outta the wounds... mamma that hurt.... I learned a lesson, always wear a leather glove, to remove a bulb like that... live and learn.

Logged

30 YEARS OF KAW.....Rich R. (the other one..) COG 5977 JUSTAMEMBAHNOWand if you are gonna call me names... it's MR. Analdweeb if you please...

All great info on the signal light socket, but I would still start with a VOM and the connection under the seat. If you don't have power at that point the fault is forward of that. If you have power then take the time to clean repair the socket or get a new one